Four years ago, in sharp contrast to the torpor and denial of the George W. Bush years, President Obama described climate change as one of humanity’s most pressing challenges and pledged an all-out effort to pass a cap-and-trade bill limiting greenhouse gas emissions.

Every wind turbine has a range of wind speeds, typically around 30 to 55 mph, in which it will produce at its rated, or maximum, capacity. At slower wind speeds, the production falls off dramatically. If the wind speed decreases by half, power production decreases by a factor of eight. On average, therefore, wind turbines do not generate near their capacity. Industry estimates project an annual output of 30-40%, but real-world experience shows that annual outputs of 15-30% of capacity are more typical.